In standard configuration, the Mercedes-AMG S63 Coupe S packs a mean punch. It’s powered by a 5.5-liter bi-turbo V-8 engine that spits out 577 horsepower and 664 pound-feet of torque, allowing it to sprint from 0 to 60 mph in 3.9 seconds to go with an electronically limited top speed of 186 mph. By most metrics, those numbers add up to a car that’s as potent as they come. Then again, that sentiment doesn’t mean much when you’re talking about a tuner like Fostla whose business has always been about giving cars like the AMG S63 Coupe S more power at their disposal. And so, the German tuner is here to present its latest tuning kit, a walloping program for the high-performance Merc that comes with an increased output of 740 horsepower and 885 pound-feet of torque.

The numbers are attention-grabbing, but they’re not the only things worth mentioning about this program. It also has some snazzy visual effects meant to bring out more personality out of the AMG S63 Coupe S. There are also a new set of wheels and tires that Fostla received from aftermarket peer Prior Design.

All told, the engine upgrade is the unquestioned showpiece of the program. Not only does it bring the output of the AMG S63 Coupe S to supercar levels, but those numbers are enough to actually up-end competing tuners and their own takes on the Mercedes.

It’s true that Fostla is entering a competitive field with this program since a lot of other tuners have kits for the same high-performance Mercedes-AMG model. Rest assured, though, Fostla makes a good account of itself with an engine upgrade that should make an impression to owners of the Mercedes-AMG S63 Coupe S.

Continue after the jump to read more about the Mercedes-AMG S63 Coupe S by Fostla

Exterior

Expectations are in order here because Fostla’s work on exterior of the Mercedes-AMG S63 Coupe S isn’t as extensive as you might be used to from other tuners. There are still some notable upgrades, including the vinyl blue chrome matte paint finish and the tinted taillights, but by and large, the changes here are kept to a minimum with no particular aerodynamic upgrades in order. The good news is that the program also includes a new set of 22-inch wheels that Fostla received from Prior Design. The wheels are then wrapped in tires measuring 265/30 and 305/25 in the front and rear, respectively.

It may not be the best of first impressions, but it’s also important to understand Fostla’s motives with this program. While some tuners are more than willing and prepared to drop a bag of aero kits on the AMG S63 Coupe S, this particular tuner’s is on that b-turbo V-8 engine. Everything else is just an icing on the cake.

What other tuners are offering

This is where Fostla’s program falls short relative to what other options are available for owners of the Mercedes-AMG S63 Coupe S. A tuner like Mansory, for example, is known as much for its comprehensive exterior upgrades as it is for its stomach-churning engine upgrades. Its program for the top-of-the-line AMG is living proof of that, thanks in large part to a carbon fiber body kit that includes items like new spoilers, wider fenders, hood vents, and extended side skirts. Oh, and let’s not forget about the massive fixed rear wing that really brings out a more aggressive look to the AMG S63 Coupe S.

Note: photo of the Mercedes-AMG S63 Coupe S Black Edition by Mansory.

If this kind of exterior work isn’t your flavor but you still want some bits and pieces of aero mods to the performance S Class, there are other options to consider. Renntech, for instance, has a prototype decklid spoiler it wants you try out. Then there are the likes of Wheelsandmore and G-Power, both of which only offer a new set of wheels as part of their tuning kits for the AMG S63 Coupe S.

Note: side-by-side photo of the Mercedes-AMG S63 Coupe by Renntech and the Mercedes-AMG S63 Coupe by G-Power.

Ultimately, Fostla’s exterior upgrade actually lines up favorably when you compare it with other tuners. The lack of aerodynamic upgrades may hurt it in some regard, but at least there are some improvements worth noting, even if they’re mostly of the cosmetic variety.

Interior

You better turn away for now if you’re expecting Fostla to have some kind of interior dress up planned for the Mercedes-AMG S63 S Coupe. For the record, there is none, although that’s not really the fault of the German tuner since a lot of its peers have approached their own programs in a similar manner. Even established aftermarket companies like G-Power, Renntech, and Wheelsandmore have made little to no effort addressing this section of the car. Since it’s a matter of preference, it’s hard to pin blame on them for taking this approach.

The good news is that it isn’t always the case. There are other tuners who take the time to work on a car’s interior. In the case of the AMG S63 Coupe S, Mansory has an extensive interior program made up of a number of premium options, including fine leather upholstery, Alcantara, carbon fiber, and in some cases, trunk decorations. Even typical “upgrades” – if you can even call them that – like the illuminated door sills and the “bespoke” floor mats are also part of Mansory’s catalog.

In some cases, a tuner pays more than its fair share of attention on the car’s interior, as was the case with Brabus and its aftermarket offering for the luxury Mercedes. if you recall, the German tuner presented a tuning program for the AMG S65 Coupe at last year’s Geneva Motor Show. One of the highlights of that kit was an interior that was dressed heavily in light brown and magnolia leather, about as good a two-tone application as we’ve seen from a tuner. Not only that, Brabus also threw in dark wood inlays and umbra-colored wood trims in the cabin, giving it a really premium look that sharply complements the corresponding work it put into the coupe’s V-8 engine.

Note: side-by-side photo of the interior of the Mercedes-AMG S63 AMG S Coupe by Mansory and the interior of the Mercedes-AMG S65 Coupe by Brabus.

Here’s the thing about interior upgrades too that people should realize. It’s the only section in the car that doesn’t get performance benefits when it’s upgraded. The cabin might look snazzier or classier, but some tuners like Fostla aren’t as keen on the luxury side as they are on the performance side of the car. Again, there’s nothing wrong with that because it really boils down to what a tuner’s rationale is when it’s developing a kit for a specific car.

Drivetrain

When you’re in the market for an aftermarket program for the Mercedes-AMG S63 Coupe S, this section is really all that matters because an argument can be made that Mercedes-AMG already did much of the work in other sections of the car. But engine upgrades are always exceptions because of their ability to unlock a car’s performance capabilities, no matter if they’re a Ford, Mercedes, or Ferrari.

In the case of the AMG S63 Coupe S, Fostla’s program for the high-performance luxury coupe revolves around a chip tuning software that’s no different from what a tuner like G-Power also has on offer for the same model. In fact, Fostla actually utilized G-Power’s Bi-Tronik 5 V1 module for this program, resulting in an increase in output to 740 horsepower and 885 pound-feet of torque. That represents a bump of 163 ponies and 220 pound-feet of torque, which is an impressive haul for a car like the AMG S63 Coupe S.

Here’s the thing though. It’s also important to ask if Fostla’s tuning program offers the biggest increase in power among all the programs for the luxury coupe that are already in the market. For that, let’s take a look at the other engine upgrades that are being offered by other tuners.

What other tuners are offering

Since we’ve mentioned Mansory a handful of times here already, let’s start there. Unlike Fostla and a host of other tuners, Mansory’s interpretation of an engine upgrade program for the AMG S63 Coupe S involves using a variety of new parts, including connecting rods, big end bearings, crankshaft, bearing bushings, a turbocharger, and a suction and compressor system. Seems like a handful, doesn’t it? Well, all those parts were put into the car’s drivetrain, helping the V-8 achieve an insane output of 887 horsepower and 960 pound-feet of torque. Even more ridiculous was Mansory tweaking the engine even further and scooping up an extra 98 ponies and 74 pound-feet of torque to bring the total output up to an incomprehensible 985 horsepower and 1,034 pound-feet of torque!

Suffice to say, Mansory’s program for the AMG S63 Coupe S is an exception. Other tuners with similar aftermarket offerings for the luxury coupe only get figures that are closer to Fostlia’s offering than Mansory’s. G-Power, for example, was able to get 705 horsepower and 738 pound-feet of torque on account of its Bi-Tronik 5 V1 tuning module. Renntech offered a similar software upgrade and it was able to produce 708 horsepower and 839 pound-feet of torque at the crank.

Then there are the tuners who worked on programs that included more than just software tunes. Wheelsandmore, for instance, went with modified turbochargers with their own specially designed bearings to increase the V-8’s output to 792 horsepower and 837 pound-feet of torque. Brabus also added hardware and software upgrades to its program, including a special billet crankshaft with a longer stroke was also put in place, a high performance exhaust, a reprogrammed ECU unit. The result is an output of 887 horsepower and 1,106 pound-feet of torque, the closest increase we have so far to Mansory’s program.

Check out the table below to see a comparison on all these tuners and the numbers they were able to get out of their respective programs for the Mercedes-AMG S63 Coupe S.

Pricing

It’s probably telling that for all the modifications and upgrades included in this program, the cost amounts to somewhere in the vicinity of €25,000, which converts to just north of $26,500. It’s not a cheap program by any means, but for this price and the price of a Mercedes-AMG S63 S Coupe, I don’t think it would be too much of an issue for owners of the luxury coupe to write a check for this amount to Fostla to get the necessary work done on the car.

Competition

Mercedes-AMG S63 Coupe G-Power

The popularity of the Mercedes-AMG S63 Coupe is evident by the number of tuners that already have programs for the car on the market. we’ve already mentioned a number of time so let’s revisit the ones that provide the closest comps to Fostla’s offering. G-Power’s program for the AMG S63 is a lot like Fostla’s, and it’s not just because both use the former’s tuning module. Exterior and interior upgrades are also minimal on G-Power’s program, leaving the focus all on the engine upgrade, which hits up to 705 horsepower and 738 pound-feet of torque, enough to boost the coupe’s 0-to-60-mph sprint time to 3.8 seconds before hitting a top sped of 205 mph.

Read our full review here.

Mercedes-AMG S63 Coupe by Renntech

>

Another software tune-driven program, Renntech’s work on the AMG S63 Coupe revolves around upgrades to the engine’s ECU unit, as well as additions like new sport mufflers with electronic valves. It seems like a relatively straighforward approach, but the German tuner was still able to increase the 5.5-liter bi-turbo V-8 engine’s output to 708 horsepower and 839, enough to propel the coupe to go from an idle position to running 60 mph in just 3.4 seconds before hitting a quarter-mile in just 11.37 seconds at 125 mph.

Read our full review here.

Conclusion

With so many options to choose from, picking which aftermarket program for the Mercedes-AMG S63 Coupe is tricky and difficult. Ultimately, though, the best advice we can make is to know what your priorities are when you’re in the market for a tuning kit. If you want overblown programs that dramatically changes every section of the car, Fostla’s offering may not be suitable for you. But if you want a relatively simple upgrade without the smallest of bells and whistles but with matching performance improvements, the German tuner has one that’s worth looking into.